1. Field of the Invention
The present invention relates generally to vehicular suspensions systems, and in particular is concerned with a dynamic absorber combined with a hydraulic damper to provide desired damping of the sprung and unsprung portions of a vehicle.
2. Description of the Related Art
Conventional vehicular suspension systems include springs mounted between the wheels and the body and pneumatic tires which provide a spring force between the wheels and the ground. Many systems utilize hydraulic dampers, i.e., shock absorbers and struts, to dampen oscillations that occur due to road inputs and body motions.
Two distinct ranges of oscillations occur in suspension systems. First, the frequency of the sprung mass (vehicular body and any load it carries) results in a "basic ride frequency" of approximately 1-2 Hz. Second, the frequency of oscillations of the unsprung mass (wheels, tires, axles, brakes, and a portion of each spring) is in the range of approximately 12-14 Hz. The higher frequency of the unsprung mass is commonly known as "wheel hop."
A high or firm damping rate is desirable to reduce the effect of wheel hop on driving stability and comfort. A low or soft damping rate is desirable to dampen the relatively lower frequency of the body. Traditionally, a hydraulic damper is tuned at one setting to address both frequencies of the suspension system, oftentimes compromising between ride comfort and stability to provide a desired type of ride to a driver and passengers.
The art continues to seek improvements. It is desirable to provide economical, hydraulic dampers to independently control both body and wheel hop frequencies. Furthermore, it is desirable to provide such dampers in a package suitable for conventional damper mounting arrangements.